a newbie - pl/sql problem

Hello,

I'm trying to do sth like this:

declare cursor x is (select * from user_tables where table_name='abc'; begin

    if x%found then

        drop table abc;
    end if;
end;
.

/

or, "equivalently" (I know there're errors because otherwise it'd work but I suppose my intension are quite clear to you...):

begin

    if (select count(*)m form user_tables where yable_name='abc')>0 then

        drop table abc;
    end if;
end;
.

/

And it does not work. As far as I've realized there are two problems: the very condition isn't proper and enforcing dropping the table this way on Oracle also appears out of my reach...
Oh: one more. Despite doing 'set serveroutput on;' in the console, when using "put_line" or "put" in pl/sql scripts, I'm given back: "PLS-00201: identifier 'PUT_LINE' must be declared". What do I do wrong?
Thanks for all answers. :-)
Best regards.

-- 
Marcin Balcerzak